1. Field of the Invention
The present invention relates to a liquid jet recording head and a liquid supply method which are used in an ink jet recording apparatus.
2. Description of the Related Art
A recording head in an ink jet recording apparatus is configured to change an ink pressure in a pressure chamber provided on the recording head to discharge an ink droplet (a recording liquid droplet) from a discharge port, and perform recording by causing the discharged ink to adhere to a recording medium.
However, in the ink jet recording method which ejects the ink droplet according to the above described principle, when bubbles enter into the pressure chamber, unintended change of the ink pressure occurs, and a printing operation may become unstable. Thus, when bubbles enter into the recording head or bubbles are generated in the recording head, it is necessary to remove these bubbles.
When the recording head is left without any special protection such as a protection cap, color materials or solvents may condense due to water vaporization from a discharge port. As a result, ink viscosity increases, and may cause adverse effects on a discharging speed and a discharging direction. To avoid generation of residual bubbles and viscosity increase in the recording head which adversely affects a discharge performance, it is known that an ink circulation flow passing through the pressure chamber is effectively generated.
FIG. 9 illustrates a schematic configuration of an example of a main part of a conventional ink jet recording head in a horizontal cross section. In this configuration, the ink jet recording head includes a plurality of pressure chambers 44 which have discharge energy generation elements 43 arranged in a row, and ink chambers 45 provided on both sides of the pressure chambers 44. The ink chambers 45 are configured to store an ink to be supplied to the pressure chambers 44. Further, the ink jet recording head includes an ink inlet port 40 which communicates with one ink chamber 45, and an ink outlet port 41 which communicates with another ink chamber 45. Furthermore, a partition wall 42 for forming the pressure chambers 44 is provided in the ink jet recording head.
When ink is discharged from the pressure chambers 44, the ink is supplied from the ink chambers 45 located on both sides of the pressure chambers 44, to the pressure chambers 44. When the ink jet recording head removes bubbles generated in the pressure chambers 44, ink is introduced from the ink inlet port 40, and then discharged from the ink outlet port 41. Consequently, an ink circulation flow 46 is formed in which the ink flows through a route including the ink inlet port 40, the ink chamber 45, the pressure chambers 44, the ink chamber 45, and the ink outlet port 41. The ink circulation flow 46 can remove the bubbles in the pressure chambers 44. (Refer to Japanese Patent Application Laid-Open No. 07-164640)
The ink circulation flow 46 flowing from the ink inlet port 40 to the ink outlet port 41 is a linear flow in the pressure chambers 44. Thus, in the pressure chambers 44 which are in the vicinity of a straight line connecting the ink inlet port 40 and the ink outlet port 41, the ink circulation flow 46 passing therethrough can be easily generated. However, in the pressure chambers 44 which are distantly positioned from the straight line connecting the ink inlet port 40 and the ink outlet port 41, the ink circulation flow 46 passing therethrough is hardly generated.
Therefore, in order to generate the ink circulation flow 46 in all pressure chambers 44, the ink chambers 45 is made large so that the ink inlet port 40 and the ink outlet port 41 may be located far from the pressure chambers 44. Further, the partition walls 42 forming the pressure chambers 44 are made long. By taking such a configuration, it is necessary that a flow path connecting the ink inlet port 40, the ink outlet port 41, and the pressure chambers 44 becomes a straight line as much as possible. In this way, the flow path of the ink circulation flow 46 is formed to allow the ink to easily flow from the ink inlet port 40 into each pressure chamber 44. Such configuration makes it difficult to reduce a size of the ink jet recording head.
When nozzle resolution is increased by forming multiple rows of the pressure chambers and integrating nozzles, the ink inlet port 40 and the ink outlet port 41 are alternately arranged so as to sandwich each row of the pressure chambers between the ink inlet port 40 and the ink outlet port 41. In order to generate the ink circulation flow 46 passing through each pressure chamber 44, directionality of the ink circulation flow 46 needs to be improved and it is necessary to provide a thicker partition wall 42 than a case of a single row in the pressure chamber 44.
Further, when the multiple rows of the pressure chambers 44 are provided, it is necessary to place the pressure chambers in a staggered arrangement, that is, each pressure chamber 44 is not arranged in the same position in a column direction, and a pressure chamber 44 in one row is positioned between pressure chambers 44 in another row. Therefore, when the pressure chambers 44 are formed in the multiple rows, it is difficult to downsize the ink jet recording head.